The M59 isn't going to much bigger. You should really be looking at something larger, like the Coolermaster 690, Antec 900 (or 902) or HAF 922.
I personally would just stick to the 300. Clean up the cables as best you can, and live with it. No reason to spend good money when you already have a good case.
Thanks i was just thinking of getting a Sparkle GTX 460 1GB instead